What is COPD? National Heart Lung and Blood Institute (NHLBI) website. Available at:
http://www.nhlbi.nih.gov/health/health-topics/topics/copd. Updated May 22, 2014. Accessed September 15, 2015.

What you can do about a lung disease called COPD. Global Initiative for Chronic Obstructive Lung Disease website. Available at:
http://www.goldcopd.org/uploads/users/files/GOLD%5FPatient%5FRevJan10.pdf. Published April 2002. Accessed September 15, 2015.